A large series of condensation products of all trans retinal with available and newly prepared 1,3-diketones has been prepared. Relationship between biological activity, photostability and structure has been established. Chemical transformation in ring A of retinylidene dimedone, one of the more promising compounds prepared, has been executed. Several new derivatives of all-trans retinoic acid, the most active compound found thus far, have been prepared, including esters and amides.